High-temperature oxidation behaviour of model Co-Re-Cr alloys at low oxygen partial pressure

摘要

The oxidation behaviour of four model Co-Re-Cr alloys and a commercial Co-based alloy was investigated at 1000℃ and a low-oxygen partial pressure of p(O_2)=10~(-16) bar, in order to prove the feasibility of a pre-oxidation treatment. Under suitable conditions of the pre-oxidation treatment, the oxidation of the highly reactive alloying element Cr is possible. All the studied alloys form a continuous and dense Cr_2O_3 scale on the metal surface. The transport of chromium to the surface occurs mainly from the Cr-rich s-phase, which becomes completely dissolved in the surrounding matrix after long exposure times. As a result of the Cr_2O_3 scale, growth depletion of Cr occurs in the near surface region, leading to internal oxidation.